Mobile NAS for my motor/home

[squiredude]

Hi all techies out there...

I have been trying to build a new NAS on my coach.  I have multiple WD RED drives (1x10TB, 4x4TB, 2x3TB(external))  I purchased the 10TB so I could consolidate the 2 external drives.

My problem is cost of unit and now OS.

almost 6 months ago I purchased an F2 TNAS from TerraMaster and after several weeks of tech support it was decided that the unit was defective.  TerraMaster offered to replace the unit I decided to upgrade to their F4 unit for a small charger.  I then purchased WD RED 4x4TB drives, per TerraMaster's suggestion.  Well after another 4-5 months of late night tech calls (they are in China) and their refusal to send me a replacement unit I decided to cash out (so to speak).  They let me keep the NAS and refund me half my money.  It had taken so lone I was just happy to move on.
My latest email to their tech informed me that the OS was propriety and that the drives and data would have to be scrubbed before using in another NAS.

Is there a standard of OS for NAS boxes?

My first task when I get another NAS is to determine a method of transferring all the data from one NAS to another.  Hopefully that should not be too much of a task, just time.

My question to all you RV techies is what NAS to purchase?  I am thinking I need a 5 bay diskless NAS that is very reasonably priced.

(FYI - I am your typical retired person living in my RV year round workamping to make ends meet so cost is a factor for me.)

Thanks in advance for your help and advice.

[orion7144]

I have used Synology and Qnap.  I prefer the Qnap due to the software it runs and the apps that can be installed.  Synology tends to be more expensive.  I only have the 3 disk one right now and run it in RAID 5 and it is has hot swap capability.  If I were in the market right now I would like for a used Qnap system since they are starting to incorporate the M2.1 SSD's  instead of full size hard drives.